A (meth)acrylate has a radical curability, and is widely used as a curable material in a system including only a (meth)acrylate or a system in which a (meth)acrylate and a radical polymerization initiator are mixed. In particular, a mixture of a (meth)acrylate and a photo radical generator is used as a photo curable material, and a mixture of a (meth)acrylate and a heat radical generator is used as a heat curable material.
Since a (meth)acrylate used in a curable material is generally cured only at positions where radicals are generated, it is difficult to uniformly cure a material having a shape that is unlikely to be uniformly illuminated or heated. Therefore, a special chain transfer agent is further added thereto to improve the curability (see Patent Document 1, for example).